Couples seeking infertility treatment will often be subject to in vitro fertilization treatment (IVF), wherein the meeting between an oocyte and a spermatozoa takes place outside the body. The woman is most commonly receiving treatment with exogenous hormones in order to regulate and stimulate the ovaries to develop more than the usual one preovulatory follicle which is seen during the natural menstrual cycle. Part of the treatment involves retrieving the oocytes from the preovulatory follicles of the ovaries in order for the oocytes to be matured and/or fertilised in vitro. After fertilisation and pre-embryo development, one to three pre-embryos are replaced in the woman's uterus, and she thus has the possibility of becoming pregnant and carry her own child. IVF is now an established treatment, which has been performed on a large scale for more than 20 years.
The protocols normally used for administration of exogenous gonadotropins are numerous and not without risks and disadvantages. The major disadvantages includes the risk of achieving ovarian hyper stimulation syndrome (OHSS) which in severe cases may be life-threatening, the economic costs to the couple, side effects from the gonadotropin preparations including weight gain, bloating, nausea, vomiting, the time involved with the monitoring process, and the unknown long-term cancer risk.
One way to alleviate the risks, side effects, and economic disadvantages of controlled ovarian stimulation protocols would be to retrieve immature oocytes and mature them in vitro. This approach would imply that the woman was without stimulation or received a minimal stimulation, whereas the retrieved oocytes in vitro could be subjected to hormonal treatment. Instead of stimulating the oocytes through the circulation of the woman, the oocytes could be stimulated directly in the culture dish. Obviously, this would primarily reduce/eliminate a number of the side effects mentioned above and secondary reduce the amounts of hormones used for the treatment.
Therefore, a number of studies have focused on the in vitro maturation (IVM) of human oocytes—and oocytes from other mammalian species. Successful maturation of human oocytes obtained from follicles which have not been affected by the mid-cycle surge of gonadotropins or a large bolus of exogenous hCG has been reported (Cha, et al, 1991, Trounson et al., 1994, Barnes et al., 1996, Russell et al., 1997, Mikkelsen, 1999).
The criteria for success were measured as the ability of the oocyte to sustain fertilization, often in connection with intracytoplasmic sperm injection (ICSI). However, the developmental competence of the embryos after replacement in the uterus is low and only a small number of babies has been born resulting from in vitro maturation of oocytes (Trounson et al., 1994, Barnes et al., 1996, Cha and Chian, 1998, Mikkelsen et al., 1999).